The estimation of the ash is made by evaporating 100 c.c. of the sample in a weighed platinum dish to dryness, and incinerating the residue at a rather moderate heat, so as to avoid volatilisation of the chlorides. The amount of ash in normal beer should never exceed 0·5 per cent., the usual proportion being about 0·3 per cent.; this would naturally be increased by the addition of sodium bicarbonate or sodium chloride to the beer. The complete analysis of the ash is seldom necessary, but it is often of importance to estimate the amount of sodium chloride contained. This is effected by dissolving the ash-residue in distilled water and precipitating the chlorine from an aliquot portion of the solution by silver nitrate; one part of the precipitate obtained represents 0·409 part of common salt. The proportion of sodium chloride in pure beer is very inconsiderable, but it may be added to the beverage either to improve the flavour or to create thirst. For the determination of phosphoric acid, a weighed portion of the ash is dissolved in nitric acid, the solution evaporated to dryness, and the residue boiled with water containing a little nitric acid. It is then filtered, concentrated by evaporation, an excess of ammonium molybdate solution added, and the mixture set aside for about ten hours, after which the precipitate formed is separated by filtration and dissolved in ammonium hydroxide. A solution of magnesium sulphate (mixed with a considerable quantity of ammonium chloride) is now added, and the precipitated ammonio-magnesium phosphate collected, washed, ignited, and weighed, 100 parts of this precipitate contain 64 parts of phosphoric anhydride (P_{2}O_{5}).